#include<bits/stdc++.h>
using namespace std;
int sum = 1;
void f(int a){
	if(a > 1){
		for(int i = 1 ; i <= a / 2 ; i++){
			f(i);
			sum = sum + 1;
		}
	}
}
int main(){
	freopen("count.in", "r", stdin);
	freopen("count.out", "w", stdout);
	int n;
	cin >> n;
	f(n);
	cout << sum << endl;
	return 0;
}
